Neil Clayton

I don't know enough to say for sure. The 2k pull up is before the diodes, not after at it would have bee at the board. Other than that I can't say. Before I went ahead, I re-did all the tests I'd done before, and for sure, it didn't work. So I can only assume that the on board resistor (guessing it was a pull up) was somehow different (I have no idea how). All I know is it now works.

So, I got impatient Started by carefully cutting the trace on the board. Verified no connection. Then put 3 diodes in line. This worked, mostly, except when AC was supposed to be off, 4V measured ~0v ish. Guessing it might be floating? I pulled it to 12v with a 2k resistor before the diodes. Everything now works! All fan speeds work, AC compressor is engaged/disengaged, and all turns off when you either turn off AC or switch off fan. Yay. Thanks for the help.

Taken me ages to get back to this, but now I have room to work. Before I cut the track on the ECU or attempt to remove the resistor, wanted to check I'm modifying the right thing. So far, I've been working off this diagram. According to pinouts as per wiring info in Link help, I map DI1 -> 4V = AC Request, and DI5 -> 4AG = AC Switch Before I go further: 1) do I even need to do anything with DI5? I think when I was measuring (the first posts) I hadn't done anything to it. 2) I didn't have DI5 setup as per diagram in initial measures. Might this have thrown off results when measuring DI1? 3) I've seen other diagrams using no pull up/down resistors to the left/right of the diodes (but they might be for g4+ boards). I presume those resistors are still required (especially if I'm about to remove existing pull up from the ECU board)? Or can I leave them off and just go with the diodes?

@Adamwcan you fling me more details please?

Yep, can give that a go.

thanks - if it all gets "too hard" I'm quite happy to write code and slap an arduino on it. it's just that that seems, a little ... extreeme

@Adamw any further ideas?

OK. With 500ohm resistor: Off, 12.54v 1. 1.55v, then 3.54 when AC clutch is OFF 2. 1.8-1.9v. 3.57 with AC clutch OFF 3. 2.85-2.9 (AC clutch never switches on) 4. 2.57-2.62 (AC clutch never switches on)

I will try lower ohms later, got a bit on at the mo. Appreciate the continued replies. v1.2 for both boards as it turns out.

With 1.5k fitted to ground, and car running: Fan speeds, v reading: 1. 1.65 2. 1.90-2.12 3. 3.01 4. 2.8 same as before, fans 1/2 works, fan 3/4 not (guessing it has to be ~below 2v)

after or before the diodes? I've tried after, (1.5k, 10k and 20k) and this results in similar behaviour. The voltage is pulled a little lower with less resistence in circuit, but still ~8 -> 10v across all fan settings. I'll remeasure today; but when off the resistence between (before diodes) from ACReq -> ground is about 2kOhm. I'll try with car on to see if this changes as well.

s7/8

Hi, Trying to get aircon working on an FD3S with a v1.2 board G4. AirCon Req (DI1) is set to LOW, with pull up OFF. If I connect the signal directly, I get: Off: 13.9 1: 1.6v 2: 1.7 - 1.9v 3: 2.9v 4: 3.6v and, as others have seen, AC works on fan1 and fan2 only. So. Diodes. If I put two diodes (1N4148) in series... nothing works. Diagram is: ECU <- |--- <- |--- <- DI/ACReq from loom. where |--- is the diode. (black band towards ECU) The signal current is 8.4ma. I read the same 1.6v (etc) on the non-ecu side of the diode pair, but the ECU side just reads 12v. I've tested the diodes and there's an expected 1.2v drop across both in series. So I don't understand ... it's like the diodes arent working. Or the signal isnt getting through. I've tried pulling the ECU side to low via a 22k resistor (only cos I saw that on another diagram, not because I know what I'm doing). no change. Any help / tips?

"still wires connected to the RS232 pins you will lose comms" - do you mean, even if those pins aren't connected to anything? They are attached to the ECU PCB @ the PCB, and go to the female (black) comms plug, but there's no electrical connection to anything RS232. i.e: the male plug connected here has been chopped up, and only has green/white CAN lines electrically connected to anything. I would have thought there would be no difference in leaving those RS232 lines disconnected @ the plug (male side) vs disconnecting at the ECU PCB itself. Are you saying that I need to physically disconnect the RS232 pins from the ECU PCB? The dash itself is a black box, with no configuration. It's fine if I cant get it to work with the G4, it was an experiment after all. Still, I'd like to know if I'm supposed to be able to run a CAN BUS and have my laptop also connected to the G4 while doing so (two different connectors; CAN on the black one; USB to the laptop on the red other one)

Right, sorry - I didn't mean to confused with ODB2. The dash, I assume, is using the CAN H/L of that connector. That's what I'm trying to make use of anyway; OBD2 is only a part of this because of that physical connector. I've disconnected the RS232, and I'm only running the CAN H/L lines from the comms connector. I *was* previoulsy using RS232 to read from the dash, but havn't used it for a number of years now and havn't revisted that old project. At the time of writing; the RS232 connection from removed/disconnected from that same cable. The PCLink is connected via the 2nd USB connection (red ringed connector) cable to the ECU.

Seems to me it's got serial 10926 tho.... so shouldn't need the free mod

I'm trying to get an inexpensive CAN dash working with the G4. It's one of the OBD2 plugin units; and is apparently capable of CAN-BUS. No way to really verify that's what it's using (it'll do ISO9141 as well)... it works on another car; but without a scope not sure how I'd know more... My question is this: should I be able to run the G4 with configured CAN, plugged into the PC Link software, at the same time? What's happening is that as soon as I plug into the RS232/CAN connector, the PC USB stops sending data to PCLink. The dash doesn't work; but before I tripple check my CAN wiring and do more digging, I'd like to know if the above scenario is normal or indicates a fault on my part. From what I can tell I've got the CAN wiring OK: I'm seeing 120ohm across the disconnected dash unit (so its got its own termination), thus im connecting it directly to the H/L output pins of the G4. F12 does show CAN as having errored out. I'm a bit puzzled why, unless its due to me unplugging/pluggin in while I test. Using ECU 4.10.2, bootcode 1.4 Board revision is: v1.2 I've included some pics to show setup:

Thanks Scott. I hadn't 'grasped' that it was an entirely separate connector. THAT'll explain why I don't see much over the other tuning connector

I've Link G4 Plugin. The manual says that there's some RS232 pinouts on the ECU connector. I'd like to confirm that this is indeed the case (primarily because I don't seem to be able to talk to it). Is it expected that assuming I have my baud rate setup correctly, that I'd be able to power on the ECU - and send it a 'W' command to do a status check? Â I'd expect to be able to send W and see 'something' on my telnet session (I'm connecting via a Ethernet->Serial converter that we've checked is working OK). The ECU itself is in the car, working, configured - and I can talk to it fine over the USB link using the PCLink s/w. Is there anything I have to configure apart from Baud, bits, parity on the ECU before it'll talk to me over serial? Thanks in advance, Neil